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RE: [TCML] NST Measurements
Hey Gary,
Why not dope some distilled water with copper sulfate and make a water
resistor? Jim Lux has a good write up on it. Wouldn't the power be 450watts?
15000v/500000ohm =30ma I^2* 500000=450 watts?
Jim Mora
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Lau, Gary
Sent: Wednesday, January 21, 2009 8:12 AM
To: Tesla Coil Mailing List
Subject: RE: [TCML] NST Measurements
Bart wrote:
> My measured output at 120.2V input was 16390 which is a voltage ratio of
> 136 (not 125 as spec'd).
I wonder what the secondary voltage would measure if it were loaded with a
30mA load? Unfortunately that requires a 500K/750W resistor - not something
I have in my junkbox.
How linear is the 136X forward ratio over the 0-120V input range? Could a
much lower wattage 500K load be used at a reduced input voltage to predict
the full-power loaded voltage?
Regards, Gary Lau
MA, USA
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of bartb
> Sent: Tuesday, January 20, 2009 11:53 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] NST Measurements
>
> Hi All,
>
> I made some extreme low voltage measurements:
>
> Feed Meas. Integer
> Vsec Vpri Ratio
> ----- ----- -----
> 120.2 684mV 176
> 110.5 625mV 177
> 100.7 565mV 178
> 090.1 502mV 180
> 080.5 445mV 181
> 070.5 386mV 183
> 060.1 326mV 184
> 050.4 271mV 186
> 040.6 216mV 188
> 030.1 158mV 190
> 020.1 104mV 193
> 010.2 52.5mV 195 **
> 008.15 42.1mV 194 **
> 006.06 31.1mV 195 **
> 004.02 20.6mV 195 **
> 002.106 10.8mV 195 **
> 001.069 5.5mV 194 **
>
> This data presents some obvious questions.
>
> When I managed a low enough level (10V down to 1V), the voltage ratio
> showed about 195 consistently (what was affecting the voltage ratio
> seems to have stopped). Did I manage to get below shunt inductance
> influence? Is it possible the turns ratio is 200, yet the voltage ratio
> is entirely something different thanks to the shunts at greater voltages
> (and the manufacturers account for this in their Voc rating)?
>
> My measured output at 120.2V input was 16390 which is a voltage ratio of
> 136 (not 125 as spec'd). Voltage ratios and assumed turn ratios are very
> different. There is now no doubt about that, but still, how to determine
> the real turns ratio is a mystery (and maybe not possible?).
>
> Bart
>
> bartb wrote:
> > Hi Dave,
> >
> > Yes, I agree. The magnetic shunts are causing the non-linearity. As I
> > mentioned a moment ago in my reply to Phil, the voltage ratio is
> > non-linear because of this. Were trying to use the voltage ratio to
> > determine turns ratio. This won't work "IF" the shunts have influence
> > because it affects the voltage ratio. I think everyone measuring is
> > seeing this affect.
> >
> > The problem I have is the inductance factor is based on the turns
> > ratio. So, how to remove shunt influence? The only way I can think of
> > is to use "extreme" low voltages. Maybe instead of inserting 120Vac to
> > the secondary, we need to bring down the voltage to something between
> > 1 and 10V input to the secondary and measure the millivolts at the
> > primary? There must be a point at which the shunts have little affect
> > and the voltage ratio becomes linear enough for a decent approximation.
> >
> > Take care,
> > Bart
> >
> > sparktron01@xxxxxxxxxxx wrote:
> >> Bart
> >>
> >> Is it possible that the inductance varying is hosing the apple cart?
> >>
> >> Instanteous voltage for an inductor (complete) is:
> >> V = iR + L (di/dt) + i (dL/dt)
> >>
> >> The last term in "linear" circuits tends to zero and (usually) has
> >> no bearing on circuit. But with a magnetically shunted circuit
> >> the third term starts influencing the second, and vice versa
> >> (i.e the whole circuit becomes VERY non-linear...)
> >>
> >> Regards
> >> Dave Sharpe, TCBOR/HEAS
> >> Chesterfield, VA. US
> >
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